Metalworking fluid compositions and preparation thereof

ABSTRACT

A metalworking fluid composition comprising an isomerized base oil having consecutive numbers of carbon atoms and less than 10 wt % naphthenic carbon by n-d-M is provided. The metalworking fluid has reduced mist formation, low foaming tendency and excellent air release properties, and excellent wear properties.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of copending application Ser.Nos. 11/831,910, filed Jul. 31, 2007, Ser. No. 11/831,896, filed Jul.31, 2007 and Ser. No. 13/045,816, filed Mar. 11, 2011 and claimspriority therefrom.

TECHNICAL FIELD

The invention relates generally to metalworking compositions exhibitingimproved anti-mist properties, having a low foaming tendency excellentair release properties, and excellent wear properties.

BACKGROUND

In industrial metal cutting operations or in the semiconductor industryfor cutting silicon wafers, machining or metalworking fluids areemployed. Metalworking fluids are used as cutting oils, rolling oils,drawing oils, pressing oils, forging oils, abrasive working oils foraluminium disks, abrasive oils for silicon wafers and coolants. Inhigh-speed machining operations that require rapid fluid application andrecirculation, foam and air entrainment are sometimes experienced withundesirable results. Foaming is undesirable because it may reducecooling at the workpiece-tool contact zone and causes containmenttransport and control problems. Various methods or strategies have beenimplemented to eliminate or reduce foaming, including the addition offoam control agent(s) when manufacturing the product or while the fluidis in-service. The use of certain foam control agent(s) such as such assilicon-based foam inhibitors leaves residues on machined parts, makingit rather difficult to subsequently paint the parts. Additionally forsome foam control agent(s), their use is generally found to worsen themetalworking fluid's air release properties. Poor air release propertiescan lead to air entrainment issues and cavitation.

Besides the foaming problem, there is a different problem oftenassociated in the use of the metalworking fluids that is of fog or mistgeneration. During the cutting process, a small amount of cutting oil isthrown off into the surrounding air as micro-sized droplets known as amist. Workers in the vicinity are exposed to the mist and, unless aprotective breathing apparatus is worn, a portion of the mist may bedrawn into the workers' lungs. While metal cutting fluids in the priorart are essential for metal forming and machining, they are currentlybeing examined with increased scrutiny because of possible hazardsassociated with worker exposure.

Various additives have been tried in the prior art to reduce theformation of fog, including the use of minor amounts of at least one ofpolyisobutene, poly-n-butene and mixtures thereof, having a viscosityaverage molecular weight ranging from 0.3 to 10 million. Rhamsan gum,hydrophobic and hydrophilic monomers, styrene or hydrocarbyl-substitutedstyrene hydrophobic monomers and hydrophilic monomers are amongst otheradditives suggested for use to reduce the mist formation. Some metalcutting fluids in the prior art with the use of various additives poseenvironmental problems associated with their disposal. There is nowuniversal agreement on the need for safer more environmentally friendlymetalworking fluids.

Recent reforming processes have formed a new class of oil, e.g., FischerTropsch base oil (FTBO), wherein the oil, fraction, or feed originatesfrom or is produced at some stage by a Fischer-Tropsch process. Thefeedstock for a Fischer-Tropsch process may come from a wide variety ofhydrocarbonaceous resources, including biomass, natural gas, coal, shaleoil, petroleum, municipal waste, derivatives of these, and combinationsthereof. Crude product prepared from the Fischer-Tropsch process can berefined into products such as diesel oil, naphtha, wax, and other liquidpetroleum or specialty products. In a number of patent publications andapplications, i.e., US 2006/0289337, US2006/0201851, US2006/0016721,US2006/0016724, US2006/0076267, US2006/020185, US2006/013210,US2005/0241990, US2005/0077208, US2005/0139513, US2005/0139514,US2005/0133409, US2005/0133407, US2005/0261147, US2005/0261146,US2005/0261145, US2004/0159582, U.S. Pat. No. 7,018,525, U.S. Pat. No.7,083,713, U.S. application Ser. Nos. 11/400,570, 11/535,165 and11/613,936, which are incorporated herein by reference, an isomerizedbase oil is produced from a process in which the feed is a waxy feedrecovered from a Fischer-Tropsch synthesis. The process comprises acomplete or partial hydroisomerization dewaxing step, using adual-functional catalyst or a catalyst that can isomerize paraffinsselectively. Hydroisomerization dewaxing is achieved by contacting thewaxy feed with a hydroisomerization catalyst in an isomerization zoneunder hydroisomerizing conditions.

There is a need for an improved metalworking fluid with reduced mist andfoam formation, excellent air release properties as compared to thecompositions of the prior art, and excellent wear properties.Additionally, there is a need for an environmentally friendlymetalworking fluid.

SUMMARY OF THE INVENTION

In one embodiment, there is provided a metalworking fluid comprising alubricant base oil having consecutive numbers of carbon atoms and lessthan 10 wt % naphthenic carbon by n-d-M; and 0.10 to 10 wt. %. of atleast an additive selected from the group of a metalworking fluidadditive package; metal deactivators; corrosion inhibitors;antimicrobial; anticorrosion; extreme pressure agents; antifriction;antirust agents; polymeric substances; anti inflammatory agents;bactericides; antiseptics; antioxidants; chelating agents such as edeticacid salts, and the like; pH regulators; antiwear agents; and mixturesthereof, and wherein the metalworking fluid has an average mistaccumulation rate of less than 300 mg/mm³ within 30 seconds after startin an aerosol mist formation test. In another embodiment, themetalworking fluid has an average mist accumulation rate of less than150 mg/mm³ in the first 60 seconds of the test.

In another aspect, there is provided a method to reduce the mistformation in a metalworking fluid, the method comprising blending acomposition comprising a lubricant base oil having consecutive numbersof carbon atoms and less than 10 wt % naphthenic carbon by n-d-M; and0.10 to 10 wt. %. of at least an additive selected from the group of ametalworking fluid additive package; metal deactivators; corrosioninhibitors; antimicrobial; anticorrosion; extreme pressure agents;antifriction; antirust agents; polymeric substances; anti inflammatoryagents; bactericides; antiseptics; antioxidants; chelating agents suchas edetic acid salts, and the like; pH regulators; antiwear agents; andmixtures thereof, for a metalworking fluid having an average mistaccumulation rate of less than 300 mg/mm³ within 30 seconds after startin an aerosol mist formation test

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1-3 are graphs illustrating the mist accumulation rates ofExamples 7-13 in an aerosol mist formation test.

DETAILED DESCRIPTION

The following terms will be used throughout the specification and willhave the following meanings unless otherwise indicated.

As used herein, the term “metalworking fluid” may be usedinterchangeably with “metalworking composition,” “metal removal fluid,”“cutting fluid,” “machining fluid,” referring to a composition that canbe used in industrial metal cutting, metal forming, metal protecting,metal treating, metal grinding operations or in the semiconductorindustry wherein the shape of the final object, e.g., silicon wafer ormachine part, is obtained by with or without the progressive removal ofmetal or silicon. Metalworking fluids amongst other functions, are usedto cool and to lubricate.

“Fischer-Tropsch derived” means that the product, fraction, or feedoriginates from or is produced at some stage by a Fischer-Tropschprocess. As used herein, “Fischer-Tropsch base oil” may be usedinterchangeably with “FT base oil,” “FTBO,” “GTL base oil” (GTL:gas-to-liquid), or “Fischer-Tropsch derived base oil.”

As used herein, “isomerized base oil” refers to a base oil made byisomerization of a waxy feed.

As used herein, a “waxy feed” comprises at least 40 wt % n-paraffins. Inone embodiment, the waxy feed comprises greater than 50 wt %n-paraffins. In another embodiment, greater than 75 wt % n-paraffins. Inone embodiment, the waxy feed also has very low levels of nitrogen andsulphur, e.g., less than 25 ppm total combined nitrogen and sulfur, orin other embodiments less than 20 ppm. Examples of waxy feeds includeslack waxes, deoiled slack waxes, refined foots oils, waxy lubricantraffinates, n-paraffin waxes, NAO waxes, waxes produced in chemicalplant processes, deoiled petroleum derived waxes, microcrystallinewaxes, Fischer-Tropsch waxes, and mixtures thereof. In one embodiment,the waxy feeds have a pour point of greater than 50° C. In anotherembodiment, greater than 60° C.

“Kinematic viscosity” is a measurement in mm²/s of the resistance toflow of a fluid under gravity, determined by ASTM D445-06.

“Viscosity index” (VI) is an empirical, unit-less number indicating theeffect of temperature change on the kinematic viscosity of the oil. Thehigher the VI of an oil, the lower its tendency to change viscosity withtemperature. Viscosity index is measured according to ASTM D 2270-04.

Four ball wear test is defined in ASTM D4172-94

Cold-cranking simulator apparent viscosity (CCS VIS) is a measurement inmillipascal seconds, mPa·s to measure the viscometric properties oflubricating base oils under low temperature and high shear. CCS VIS isdetermined by ASTM D 5293-04.

The boiling range distribution of base oil, by wt %, is determined bysimulated distillation (SIMDIS) according to ASTM D 6352-04, “BoilingRange Distribution of Petroleum Distillates in Boiling Range from 174 to700° C. by Gas Chromatography.”

“Noack volatility” is defined as the mass of oil, expressed in weight %,which is lost when the oil is heated at 250° C. with a constant flow ofair drawn through it for 60 min., measured according to ASTM D5800-05,Procedure B.

Brookfield viscosity is used to determine the internal fluid-friction ofa lubricant during cold temperature operation, which can be measured byASTM D 2983-04.

“Pour point” is a measurement of the temperature at which a sample ofbase oil will begin to flow under certain carefully controlledconditions, which can be determined as described in ASTM D 5950-02.

“Auto ignition temperature” is the temperature at which a fluid willignite spontaneously in contact with air, which can be determinedaccording to ASTM 659-78.

“Ln” refers to natural logarithm with base “e.”

“Traction coefficient” is an indicator of intrinsic lubricantproperties, expressed as the dimensionless ratio of the friction force Fand the normal force N, where friction is the mechanical force whichresists movement or hinders movement between sliding or rollingsurfaces. Traction coefficient can be measured with an MTM TractionMeasurement System from PCS Instruments, Ltd., configured with apolished 19 mm diameter ball (SAE AISI 52100 steel) angled at 220 to aflat 46 mm diameter polished disk (SAE AISI 52100 steel). The steel balland disk are independently measured at an average rolling speed of 3meters per second, a slide to roll ratio of 40 percent, and a load of 20Newtons. The roll ratio is defined as the difference in sliding speedbetween the ball and disk divided by the mean speed of the ball anddisk, i.e. roll ratio=(Speed1−Speed2)/((Speed1+Speed2)−/2).

As used herein, “consecutive numbers of carbon atoms” means that thebase oil has a distribution of hydrocarbon molecules over a range ofcarbon numbers, with every number of carbon numbers in-between. Forexample, the base oil may have hydrocarbon molecules ranging from C22 toC36 or from C30 to C60 with every carbon number in-between. Thehydrocarbon molecules of the base oil differ from each other byconsecutive numbers of carbon atoms, as a consequence of the waxy feedalso having consecutive numbers of carbon atoms. For example, in theFischer-Tropsch hydrocarbon synthesis reaction, the source of carbonatoms is CO and the hydrocarbon molecules are built up one carbon atomat a time. Petroleum-derived waxy feeds have consecutive numbers ofcarbon atoms. In contrast to an oil based on poly-alpha-olefin (“PAO”),the molecules of an isomerized base oil have a more linear structure,comprising a relatively long backbone with short branches. The classictextbook description of a PAO is a star-shaped molecule, and inparticular tridecane, which is illustrated as three decane moleculesattached at a central point. While a star-shaped molecule istheoretical, nevertheless PAO molecules have fewer and longer branchesthat the hydrocarbon molecules that make up the isomerized base oildisclosed herein.

“Molecules with cycloparaffinic functionality” mean any molecule thatis, or contains as one or more substituents, a monocyclic or a fusedmulticyclic saturated hydrocarbon group.

“Molecules with monocycloparaffinic functionality” mean any moleculethat is a monocyclic saturated hydrocarbon group of three to seven ringcarbons or any molecule that is substituted with a single monocyclicsaturated hydrocarbon group of three to seven ring carbons.

“Molecules with multicycloparaffinic functionality” mean any moleculethat is a fused multicyclic saturated hydrocarbon ring group of two ormore fused rings, any molecule that is substituted with one or morefused multicyclic saturated hydrocarbon ring groups of two or more fusedrings, or any molecule that is substituted with more than one monocyclicsaturated hydrocarbon group of three to seven ring carbons.

Molecules with cycloparaffinic functionality, molecules withmonocycloparaffinic functionality, and molecules withmulticycloparaffinic functionality are reported as weight percent andare determined by a combination of Field Ionization Mass Spectroscopy(FIMS), HPLC-UV for aromatics, and Proton NMR for olefins, further fullydescribed herein.

Oxidator BN measures the response of a lubricating oil in a simulatedapplication. High values, or long times to adsorb one liter of oxygen,indicate good stability. Oxidator BN can be measured via a Dornte-typeoxygen absorption apparatus (R. W. Dornte “Oxidation of White Oils,”Industrial and Engineering Chemistry, Vol. 28, page 26, 1936), under 1atmosphere of pure oxygen at 340° F., time to absorb 1000 ml of O₂ by100 g. of oil is reported. In the Oxidator BN test, 0.8 ml of catalystis used per 100 grams of oil. The catalyst is a mixture of solublemetal-naphthenates simulating the average metal analysis of usedcrankcase oil. The additive package is 80 millimoles of zincbispolypropylenephenyldithiophosphate per 100 grams of oil.

Molecular characterizations can be performed by methods known in theart, including Field Ionization Mass Spectroscopy (FIMS) and n-d-Manalysis (ASTM D 3238-95 (Re-approved 2005)). In FIMS, the base oil ischaracterized as alkanes and molecules with different numbers ofunsaturations. The molecules with different numbers of unsaturations maybe comprised of cycloparaffins, olefins, and aromatics. If aromatics arepresent in significant amount, they would be identified as4-unsaturations. When olefins are present in significant amounts, theywould be identified as 1-unsaturations. The total of the1-unsaturations, 2-unsaturations, 3-unsaturations, 4-unsaturations,5-unsaturations, and 6-unsaturations from the FIMS analysis, minus thewt % olefins by proton NMR, and minus the wt % aromatics by HPLC-UV isthe total weight percent of molecules with cycloparaffinicfunctionality. If the aromatics content was not measured, it was assumedto be less than 0.1 wt % and not included in the calculation for totalweight percent of molecules with cycloparaffinic functionality. Thetotal weight percent of molecules with cycloparaffinic functionality isthe sum of the weight percent of molecules with monocyclopraffinicfunctionality and the weight percent of molecules withmulticycloparaffinic functionality.

Molecular weights are determined by ASTM D2503-92 (Reapproved 2002). Themethod uses thermoelectric measurement of vapour pressure (VPO). Incircumstances where there is insufficient sample volume, an alternativemethod of ASTM D2502-04 may be used; and where this has been used it isindicated.

Density is determined by ASTM D4052-96 (Reapproved 2002). The sample isintroduced into an oscillating sample tube and the change in oscillatingfrequency caused by the change in the mass of the tube is used inconjunction with calibration data to determine the density of thesample.

Weight percent olefins can be determined by proton-NMR according to thesteps specified herein. In most tests, the olefins are conventionalolefins, i.e. a distributed mixture of those olefin types havinghydrogens attached to the double bond carbons such as: alpha,vinylidene, cis, trans, and tri-substituted, with a detectable allylicto olefin integral ratio between 1 and 2.5. When this ratio exceeds 3,it indicates a higher percentage of tri or tetra substituted olefinsbeing present, thus other assumptions known in the analytical art can bemade to calculate the number of double bonds in the sample. The stepsare as follows: A) Prepare a solution of 5-10% of the test hydrocarbonin deuterochloroform. B) Acquire a normal proton spectrum of at least 12ppm spectral width and accurately reference the chemical shift (ppm)axis, with the instrument having sufficient gain range to acquire asignal without overloading the receiver/ADC, e.g., when a 30 degreepulse is applied, the instrument having a minimum signal digitizationdynamic range of 65,000. In one embodiment, the instrument has a dynamicrange of at least 260,000. C) Measure the integral intensities between:6.0-4.5 ppm (olefin); 2.2-1.9 ppm (allylic); and 1.9-0.5 ppm (saturate).D) Using the molecular weight of the test substance determined by ASTM D2503-92 (Reapproved 2002), calculate: 1. The average molecular formulaof the saturated hydrocarbons; 2. The average molecular formula of theolefins; 3. The total integral intensity (=sum of all integralintensities); 4. The integral intensity per sample hydrogen (=totalintegral/number of hydrogens in formula); 5. The number of olefinhydrogens (═Olefin integral/integral per hydrogen); 6. The number ofdouble bonds (═Olefin hydrogen times hydrogens in olefin formula/2); and7. The wt % olefins by proton NMR=100 times the number of double bondstimes the number of hydrogens in a typical olefin molecule divided bythe number of hydrogens in a typical test substance molecule. In thistest, the wt % olefins by proton NMR calculation procedure, D, worksparticularly well when the percent olefins result is low, less than 15wt %.

Weight percent aromatics in one embodiment can be measured by HPLC-UV.In one embodiment, the test is conducted using a Hewlett Packard 1050Series Quaternary Gradient High Performance Liquid Chromatography (HPLC)system, coupled with a HP 1050 Diode-Array UV-Vis detector interfaced toan HP Chem-station. Identification of the individual aromatic classes inthe highly saturated base oil can be made on the basis of the UVspectral pattern and the elution time. The amino column used for thisanalysis differentiates aromatic molecules largely on the basis of theirring-number (or double-bond number). Thus, the single ring aromaticcontaining molecules elute first, followed by the polycyclic aromaticsin order of increasing double bond number per molecule. For aromaticswith similar double bond character, those with only alkyl substitutionon the ring elute sooner than those with naphthenic substitution.Unequivocal identification of the various base oil aromatic hydrocarbonsfrom their UV absorbance spectra can be accomplished recognizing thattheir peak electronic transitions are all red-shifted relative to thepure model compound analogs to a degree dependent on the amount of alkyland naphthenic substitution on the ring system. Quantification of theeluting aromatic compounds can be made by integrating chromatograms madefrom wavelengths optimized for each general class of compounds over theappropriate retention time window for that aromatic. Retention timewindow limits for each aromatic class can be determined by manuallyevaluating the individual absorbance spectra of eluting compounds atdifferent times and assigning them to the appropriate aromatic classbased on their qualitative similarity to model compound absorptionspectra.

HPLC-UV Calibration. In one embodiment, HPLC-UV can be used foridentifying classes of aromatic compounds even at very low levels, e.g.,multi-ring aromatics typically absorb 10 to 200 times more strongly thansingle-ring aromatics. Alkyl-substitution affects absorption by 20%.Integration limits for the co-eluting 1-ring and 2-ring aromatics at 272nm can be made by the perpendicular drop method. Wavelength dependentresponse factors for each general aromatic class can be first determinedby constructing Beer's Law plots from pure model compound mixtures basedon the nearest spectral peak absorbances to the substituted aromaticanalogs. Weight percent concentrations of aromatics can be calculated byassuming that the average molecular weight for each aromatic class wasapproximately equal to the average molecular weight for the whole baseoil sample.

NMR analysis. In one embodiment, the weight percent of all moleculeswith at least one aromatic function in the purified mono-aromaticstandard can be confirmed via long-duration carbon 13 NMR analysis. TheNMR results can be translated from % aromatic carbon to % aromaticmolecules (to be consistent with HPLC-UV and D 2007) knowing that 95-99%of the aromatics in highly saturated base oils are single-ringaromatics. In another test to accurately measure low levels of allmolecules with at least one aromatic function by NMR, the standard D5292-99 (Reapproved 2004) method can be modified to give a minimumcarbon sensitivity of 500:1 (by ASTM standard practice E 386) with a15-hour duration run on a 400-500 MHz NMR with a 10-12 mm Nalorac probe.Acorn PC integration software can be used to define the shape of thebaseline and consistently integrate.

Extent of branching refers to the number of alkyl branches inhydrocarbons. Branching and branching position can be determined usingcarbon-13 (¹³C) NMR according to the following nine-step process: 1)Identify the CH branch centers and the CH₃ branch termination pointsusing the DEPT Pulse sequence (Doddrell, D. T.; D. T. Pegg; M. R.Bendall, Journal of Magnetic Resonance 1982, 48, 323ff). 2) Verify theabsence of carbons initiating multiple branches (quaternary carbons)using the APT pulse sequence (Patt, S. L.; J. N. Shoolery, Journal ofMagnetic Resonance 1982, 46, 535ff). 3) Assign the various branch carbonresonances to specific branch positions and lengths using tabulated andcalculated values known in the art (Lindeman, L. P., Journal ofQualitative Analytical Chemistry 43, 1971 1245ff; Netzel, D. A., et al.,Fuel, 60, 1981, 307ff). 4) Estimate relative branching density atdifferent carbon positions by comparing the integrated intensity of thespecific carbon of the methyl/alkyl group to the intensity of a singlecarbon (which is equal to total integral/number of carbons per moleculein the mixture). For the 2-methyl branch, where both the terminal andthe branch methyl occur at the same resonance position, the intensity isdivided by two before estimating the branching density. If the 4-methylbranch fraction is calculated and tabulated, its contribution to the4+methyls is subtracted to avoid double counting. 5) Calculate theaverage carbon number. The average carbon number is determined bydividing the molecular weight of the sample by 14 (the formula weight ofCH₂). 6) The number of branches per molecule is the sum of the branchesfound in step 4. 7) The number of alkyl branches per 100 carbon atoms iscalculated from the number of branches per molecule (step 6) times100/average carbon number. 8) Estimate Branching Index (BI) by ¹H NMRAnalysis, which is presented as percentage of methyl hydrogen (chemicalshift range 0.6-1.05 ppm) among total hydrogen as estimated by NMR inthe liquid hydrocarbon composition. 9) Estimate Branching proximity (BP)by ¹³C NMR, which is presented as percentage of recurring methylenecarbons—which are four or more carbons away from the end group or abranch (represented by a NMR signal at 29.9 ppm) among total carbons asestimated by NMR in the liquid hydrocarbon composition. The measurementscan be performed using any Fourier Transform NMR spectrometer, e.g., onehaving a magnet of 7.0 T or greater. After verification by MassSpectrometry, UV or an NMR survey that aromatic carbons are absent, thespectral width for the ¹³C NMR studies can be limited to the saturatedcarbon region, 0-80 ppm vs. TMS (tetramethylsilane). Solutions of 25-50wt. % in chloroform-dl are excited by 30 degrees pulses followed by a1.3 seconds (sec.) acquisition time. In order to minimize non-uniformintensity data, the broadband proton inverse-gated decoupling is usedduring a 6 sec. delay prior to the excitation pulse and on duringacquisition. Samples are doped with 0.03 to 0.05 M Cr (acac)₃ (tris(acetylacetonato)-chromium (III)) as a relaxation agent to ensure fullintensities are observed. The DEPT and APT sequences can be carried outaccording to literature descriptions with minor deviations described inthe Varian or Bruker operating manuals. DEPT is DistortionlessEnhancement by Polarization Transfer. The DEPT 45 sequence gives asignal all carbons bonded to protons. DEPT 90 shows CH carbons only.DEPT 135 shows CH and CH₃ up and CH₂ 180 degrees out of phase (down).APT is attached proton test, known in the art. It allows all carbons tobe seen, but if CH and CH₃ are up, then quaternaries and CH₂ are down.The branching properties of the sample can be determined by ¹³C NMRusing the assumption in the calculations that the entire sample wasiso-paraffinic. The unsaturates content may be measured using FieldIonization Mass Spectroscopy (FIMS).

In one embodiment, the metalworking fluid comprises a number ofcomponents, including optional additives, in a matrix of base oil.

Base Oil Matrix Component: In one embodiment, the base oil or blendsthereof forming the matrix comprises at least an isomerized base oilwhich the product itself, its fraction, or feed originates from or isproduced at some stage by isomerization of a waxy feed from aFischer-Tropsch process (“Fischer-Tropsch derived base oils”). Inanother embodiment, the base oil comprises at least an isomerized baseoil made from a substantially paraffinic wax feed (“waxy feed”). In athird embodiment, the base oil consists essentially of at least anisomerized base oil.

Fischer-Tropsch derived base oils are disclosed in a number of patentpublications, including for example U.S. Pat. Nos. 6,080,301, 6,090,989,and 6,165,949, and US Patent Publication No. US2004/0079678A1,US20050133409, US20060289337. The Fischer-Tropsch process is a catalyzedchemical reaction in which carbon monoxide and hydrogen are convertedinto liquid hydrocarbons of various forms including a light reactionproduct and a waxy reaction product, with both being substantiallyparaffinic.

In one embodiment the isomerized base oil has consecutive numbers ofcarbon atoms and has less than 10 wt % naphthenic carbon by n-d-M. Inyet another embodiment the isomerized base oil made from a waxy feed hasa kinematic viscosity at 100° C. between 1.5 and 3.5 mm²/s.

In one embodiment, the isomerized base oil is made by a process in whichthe hydroisomerization dewaxing is performed at conditions sufficientfor the base oil to have: a) a weight percent of all molecules with atleast one aromatic functionality less than 0.30; b) a weight percent ofall molecules with at least one cycloparaffinic functionality greaterthan 10; c) a ratio of weight percent molecules with monocycloparaffinicfunctionality to weight percent molecules with multicycloparaffinicfunctionality greater than 20 and d) a viscosity index greater than28×Ln(Kinematic viscosity at 100° C.)+80.

In another embodiment, the isomerized base oil is made from a process inwhich the highly paraffinic wax is hydroisomerized using a shapeselective intermediate pore size molecular sieve comprising a noblemetal hydrogenation component, and under conditions of 600-750° F.(315-399° C.) In the process, the conditions for hydroisomerization arecontrolled such that the conversion of the compounds boiling above 700°F. (371° C.) in the wax feed to compounds boiling below 700° F. (371°C.) is maintained between 10 wt % and 50 wt %. A resulting isomerizedbase oil has a kinematic viscosity of between 1.0 and 3.5 mm²/s at 100°C. and a Noack volatility of less than 50 weight %. The base oilcomprises greater than 3 weight % molecules with cycloparaffinicfunctionality and less than 0.30 weight percent aromatics.

In one embodiment the isomerized base oil has a Noack volatility lessthan an amount calculated by the following equation: 1000×(KinematicViscosity at 100° C.)⁻² ⁷. In another embodiment, the isomerized baseoil has a Noack volatility less than an amount calculated by thefollowing equation: 900×(Kinematic Vicosity at 100° C.)^(−2.8). In athird embodiment, the isomerized base oil has a Kinematic Vicosity at100° C. of >1.808 mm²/s and a Noack volatility less than an amountcalculated by the following equation: 1.286+20 (kv100)^(−1.5)+551.8e^(−kv100), where kv100 is the kinematic viscosity at 100° C. In afourth embodiment, the isomerized base oil has a kinematic viscosity at100° C. of less than 4.0 mm²/s, and a wt % Noack volatility between 0and 100. In a fifth embodiment, the isomerized base oil has a kinematicviscosity between 1.5 and 4.0 mm²/s and a Noack volatility less than theNoack volatility calculated by the following equation: 160−40 (KinematicViscosity at 100° C.).

In one embodiment, the isomerized base oil has a kinematic viscosity at100° C. in the range of 2.4 and 3.8 mm²/s and a Noack volatility lessthan an amount defined by the equation: 900×(Kinematic Viscosity at 100°C.)^(−2.8)−15). For kinematic viscosities in the range of 2.4 and 3.8mm²/s, the equation: 900×(Kinematic Viscosity at 100° C.)^(−2.8)−15)provides a lower Noack volatility than the equation: 160-40 (KinematicViscosity at 100° C.)

In one embodiment, the isomerized base oil is made from a process inwhich the highly paraffinic wax is hydroisomerized under conditions forthe base oil to have a kinematic viscosity at 100° C. of 3.6 to 4.2mm²/s, a viscosity index of greater than 130, a wt % Noack volatilityless than 12, a pour point of less than −9° C.

In one embodiment, the isomerized base oil has an auto-ignitiontemperature (AIT) greater than the AIT defined by the equation: AIT in °C.=1.6×(Kinematic Viscosity at 40° C., in mm2/s)+300. In a secondembodiment, the base oil as an AIT of greater than 329° C. and aviscosity index greater than 28×Ln(Kinematic Viscosity at 100° C., inmm²/s)+100.

In one embodiment, the isomerized base oil has a relatively low tractioncoefficient, specifically, its traction coefficient is less than anamount calculated by the equation: traction coefficient=0.009×Ln(kinematic viscosity in mm²/s)−0.001, wherein the kinematic viscosity inthe equation is the kinematic viscosity during the traction coefficientmeasurement and is between 2 and 50 mm²/s In one embodiment, theisomerized base oil has a traction coefficient of less than 0.023 (orless than 0.021) when measured at a kinematic viscosity of 15 mm²/s andat a slide to roll ratio of 40%. In another embodiment the isomerizedbase oil has a traction coefficient of less than 0.017 when measured ata kinematic viscosity of 15 mm²/s and at a slide to roll ratio of 40%.In another embodiment the isomerized base oil has a viscosity indexgreater than 150 and a traction coefficient less than 0.015 whenmeasured at a kinematic viscosity of 15 mm²/s and at a slide to rollratio of 40 percent.

In some embodiments, the isomerized base oil having low tractioncoefficients also displays a higher kinematic viscosity and higherboiling points. In one embodiment, the base oil has a tractioncoefficient less than 0.015, and a 50 wt % boiling point greater than565° C. (1050° F.). In another embodiment, the base oil has a tractioncoefficient less than 0.011 and a 50 wt % boiling point by ASTM D6352-04 greater than 582° C. (1080° F.).

In some embodiments, the isomerized base oil having low tractioncoefficients also displays unique branching properties by NMR, includinga branching index less than or equal to 23.4, a branching proximitygreater than or equal to 22.0, and a Free Carbon Index between 9 and 30.In one embodiment, the base oil has at least 4 wt % naphthenic carbon,in another embodiment, at least 5 wt % naphthenic carbon by n-d-Manalysis by ASTM D 3238-95 (Reapproved 2005).

In one embodiment, the isomerized base oil is produced in a processwherein the intermediate oil isomerate comprises paraffinic hydrocarboncomponents, and in which the extent of branching is less than 7 alkylbranches per 100 carbons, and wherein the base oil comprises paraffinichydrocarbon components in which the extent of branching is less than 8alkyl branches per 100 carbons and less than 20 wt % of the alkylbranches are at the 2 position. In one embodiment, the FT base oil has apour point of less than −8° C.; a kinematic viscosity at 100° C. of atleast 3.2 mm²/s; and a viscosity index greater than a viscosity indexcalculated by the equation of =22×Ln (kinematic viscosity at 100°C.)+132.

In one embodiment, the base oil comprises greater than 10 wt. % and lessthan 70 wt. % total molecules with cycloparaffinic functionality, and aratio of weight percent molecules with monocycloparaffinic functionalityto weight percent molecules with multicycloparaffinic functionalitygreater than 15.

In one embodiment, the isomerized base oil has an average molecularweight between 600 and 1100, and an average degree of branching in themolecules between 6.5 and 10 alkyl branches per 100 carbon atoms. Inanother embodiment, the isomerized base oil has a kinematic viscositybetween about 8 and about 25 mm²/s and an average degree of branching inthe molecules between 6.5 and 10 alkyl branches per 100 carbon atoms.

In one embodiment, the isomerized base oil is obtained from a process inwhich the highly paraffinic wax is hydroisomerized at a hydrogen to feedratio from 712.4 to 3562 liter H₂/liter oil, for the base oil to have atotal weight percent of molecules with cycloparaffinic functionality ofgreater than 10, and a ratio of weight percent molecules withmonocycloparaffinic functionality to weight percent molecules withmulticycloparaffinic functionality of greater than 15. In anotherembodiment, the base oil has a viscosity index greater than an amountdefined by the equation: 28×Ln(Kinematic viscosity at 100° C.)+95. In athird embodiment, the base oil comprises a weight percent aromatics lessthan 0.30; a weight percent of molecules with cycloparaffinicfunctionality greater than 10; a ratio of weight percent of moleculeswith monocycloparaffinic functionality to weight percent of moleculeswith multicycloparaffinic functionality greater than 20; and a viscosityindex greater than 28×Ln(Kinematic Viscosity at 100° C.)+110. In afourth embodiment, the base oil further has a kinematic viscosity at100° C. greater than 6 mm²/s In a fifth embodiment, the base oil has aweight percent aromatics less than 0.05 and a viscosity index greaterthan 28×Ln(Kinematic Viscosity at 100° C.)+95. In a sixth embodiment,the base oil has a weight percent aromatics less than 0.30, a weightpercent molecules with cycloparaffinic functionality greater than thekinematic viscosity at 100° C., in mm²/s, multiplied by three, and aratio of molecules with monocycloparaffinic functionality to moleculeswith multicycloparaffinic functionality greater than 15.

In one embodiment, the isomerized base oil contains between 2 and 10%naphthenic carbon as measured by n-d-M. In one embodiment, the base oilhas a kinematic viscosity of 1.5-3.0 mm²/s at 100° C. and 2-3%naphthenic carbon. In another embodiment, a kinematic viscosity of1.8-3.5 mm²/s at 100° C. and 2.5-4% naphthenic carbon. In a thirdembodiment, a kinematic viscosity of 3-6 mm²/s at 100° C. and 2.7-5naphthenic carbon. In a fourth embodiment, a kinematic viscosity of10-30 mm²/s at 100° C. and greater than 5.2 naphthenic carbon.

In one embodiment, the isomerized base oil has an average molecularweight greater than 475; a viscosity index greater than 140, and aweight percent olefins less than 10.

The base oil improves the air release and low foaming characteristics ofthe mixture when incorporated into the metalworking fluid.

In one embodiment, the isomerized base oil is a FT base oil having akinematic viscosity at 100° C. between 2 mm²/s and 6 mm²/s; a kinematicviscosity at 40° C. between 7 mm²/s and 20 mm²/s; CCS viscosity of lessthan 2300 mPa·s at −35° C.; pour point in the range of −20 and −40° C.;molecular weight of 300-500; density in the range of 0.800 to 0.820;paraffinic carbon in the range of 93-97%; naphthenic carbon in the rangeof 3-7%; Oxidator BN of 30 to 60 hours; and Noack volatility in wt. % of8 to 20 as measured by ASTM D5800-05 Procedure B.

In another embodiment for an anti-mist performance, the isomerized baseoil is a FT base oil of “light” range viscosity having a kinematicviscosity at 100° C. between 2 mm²/s and 3 mm²/s; a kinematic viscosityat 40° C. between 7 mm²/s and 25 mm²/s; a viscosity index of 120-150;pour point in the range of −20 and −50° C.; molecular weight of 300-500;density in the range of 0.800 to 0.820; paraffinic carbon in the rangeof 92-97%; naphthenic carbon in the range of 3-7%; Oxidator BN of 30 to60 hours; and Noack volatility in wt. % of 8 to 60 as measured by ASTMD5800-05 Procedure B. In another embodiment, the isomerized base oil isa FT base oil of “medium” range viscosity, having a kinematic viscosityat 100° C. between 5 mm²/s and 7 mm²/s; a kinematic viscosity at 40° C.between 25 mm²/s and 50 mm²/s; a viscosity index of 140-160; pour pointin the range of −15 and −25° C.; molecular weight of 450-550; density inthe range of 0.820 to 0.830; paraffinic carbon in the range of 90-95%.In a third embodiment, the base oil comprises a mixture of “light” and“medium” range viscosity FT base oils.

In one embodiment, the metalworking fluid employs at least one of theisomerized base oils described above. In another embodiment, thecomposition consists essentially of at least a Fischer-Tropsch base oil.In yet another embodiment, the metalworking fluid employs at least anisomerized based oil as the base oil matrix and optionally 5 to 95 wt. %of at least another type of oil, e.g., lubricant base oils selected fromGroup I, II, III, IV, and V lubricant base oils as defined in the APIInterchange Guidelines, and mixtures thereof. In a fourth embodiment,the metalworking fluid employs an isomerized based oil and 5 to 20 wt. %of at least another type of oil. Examples include conventionally usedmineral oils, synthetic hydrocarbon oils or synthetic ester oils, ormixtures thereof depending on the application. Mineral lubricating oilbase stocks can be any conventionally refined base stocks derived fromparaffinic, naphthenic and mixed base crudes. Synthetic lubricating oilsthat can be used include esters of glycols and complex esters. Othersynthetic oils that can be used include synthetic hydrocarbons such aspolyalphaolefins; alkyl benzenes, e.g., alkylate bottoms from thealkylation of benzene with tetrapropylene, or the copolymers of ethyleneand propylene; silicone oils, e.g., ethyl phenyl polysiloxanes, methylpolysiloxanes, etc., polyglycol oils, e.g., those obtained by condensingbutyl alcohol with propylene oxide; etc. Other suitable synthetic oilsinclude the polyphenyl ethers, e.g., those having from 3 to 7 etherlinkages and 4 to 8 phenyl groups. Other suitable synthetic oils includepolyisobutenes, and alkylated aromatics such as alkylated naphthalenes.

Additional Components: The metalworking fluid in one embodiment ischaracterized as having reduced mist formation, lower foaming tendency,and better air release properties compared to compositions of the priorart. Depending on the applications, e.g., straight oils (neat oils) orsoluble oils, the metalworking fluid may contain applicable additivesknown in the art to improve the properties of the composition in amountsranging from 0.10 to 10 wt. %. These additives include metaldeactivators; corrosion inhibitors; antimicrobial; anticorrosion;extreme pressure agents; antifriction; antirust agents; polymericsubstances; anti inflammatory agents; bactericides; antiseptics;antioxidants; chelating agents such as edetic acid salts, and the like;pH regulators; antiwear agents including active sulphur anti-wearadditive packages and the like; a metalworking fluid additive packagecontaining at least one of the aforementioned additives.

In different embodiments, there is no need to add any of the anti-mistadditives (mist control agents or anti-misting agents) nor the foaminhibitors in the prior art, for a metalworking fluid that consistsessentially of the base oil matrix comprising the isomerized base oiland at least an additive other than an anti-misting agent/foaminhibitor. However, in other embodiments and depending on the end-useapplications, small quantities of additives such as anti-misting agentsmay be optionally added in an amount ranging from 0.05 to 5.0% by vol.in one embodiment and less than 1 wt. % in other embodiments.Non-limiting examples include rhamsan gum, hydrophobic and hydrophilicmonomers, styrene or hydrocarbyl-substituted styrene hydrophobicmonomers and hydrophilic monomers, oil soluble organic polymers rangingin molecular weight (viscosity average molecular weight) from about 0.3to over 4 million such as isobutylene, styrene, alkyl methacrylate,ethylene, propylene, n-butylene vinyl acetate, etc. In one embodiment,polymethylmethacrylate or poly(ethylene, propylene, butylene orisobutylene) in the molecular weight range 1 to 3 million is used.

In some embodiments and for certain applications, small amount of foaminhibitors in the prior art can also be added to the composition in anamount ranging from 0.05 to 15.0 wt. %. Non-limiting examples includepolydimethylsiloxanes, often trimethylsilyl terminated, alkylpolymethacrylates, polymethylsiloxanes, an N-acylamino acid having along chain acyl group and/or a salt thereof, an N-alkylamino acid havinga long chain alkyl group and/or a salt thereof used concurrently with analkylalkylene oxide and/or an acylalkylene oxide, acetylene diols andethoxylated acetylene diols, silicones, hydrophobic materials (e.g.silica), fatty amides, fatty acids, fatty acid esters, and/or organicpolymers, modified siloxanes, polyglycols, esterified or modifiedpolyglycols, polyacrylates, fatty acids, fatty acid esters, fattyalcohols, fatty alcohol esters, oxo-alcohols, fluorosurfactants, waxessuch as ethylenebistereamide wax, polyethylene wax, polypropylene wax,ethylenebisstereamide wax, and paraffinic wax, ureum. The foam controlagents can be used with suitable dispersants and emulsifiers. Additionalactive foam control agents are described in “Foam Control Agents”, byHenry T. Kerner (Noyes Data Corporation, 1976), pages 125-162.

In various embodiment, the metalworking fluid further comprisesanti-friction agents include overbased sulfonates, sulfurized olefins,chlorinated paraffins and olefins, sulfurized ester olefins, amineterminated polyglycols, and sodium dioctyl phosphate salts. In yet otherembodiment, the composition further comprises corrosion inhibitorsincluding carboxylic/boric acid diamine salts, carboxylic acid aminesalts, alkanol amines, alkanol amine borates and the like.

In various embodiments, the metalworking fluid further comprise oilsoluble metal deactivators in an amount of 0.01 to 0.5 vol % (based onthe final oil volume). Non-limiting examples include triazoles orthiadiazoles, specifically aryl triazoles such as benzotriazole andtolyltriazole, alkyl derivatives of such triazoles, andbenzothiadiazoles such as R(C₆H₃)N₂S where R is H or C₁ to C₁₀ alkyl.Suitable materials are available from Ciba Geigy under the tradenamesIrgamet and Reomet or from Vanderbilt Chemical Corporation under theVanlube tradename.

In one embodiment, such as when the composition serves the dual purposeof cutting fluid and machine lube oil, a small amount of at least anantioxidant in the range 0.01 to 1.0 weight % can be added. Non-limitingexamples include antioxidants of the aminic or phenolic type or mixturesthereof, e.g., butylated hydroxy toluene (BHT), bis-2,6-di-t-butylphenolderivatives, sulfur containing hindered phenols, and sulfur containinghindered bisphenol.

In some embodiment, the metalworking fluid further comprises 0.1 to 20wt. % of at least an extreme-pressure agent. Non-limiting examples ofextreme pressure agents include zinc dithiophosphate, molybdenumoxysulfide dithiophosphate, molybdenum oxysulfide thithiocarbamate,molybdenum amine compounds, sulfurized oils and fats, sulfurized fattyacids, sulfurized esters, sulfurized olefins, dihydrocarbylpolysulfides, thiocarbamates, thioterpenes, dialkyl thiodipropionates,and the like.

In addition to the above additives, various other conventional additivescan be added to such extent that they do not inhibit the effects of themetalworking fluid. Examples include fatty acids and salts thereof;polyhydric alcohols such as propylene glycol, glycerin, butyleneglycerol, and the like; surfactants such as anionic surfactants,amphoteric surfactants, nonionic surfactants, and the like; and boronnitride dispersed in a dispersant such as a surfactant.

Method for Making: The optional additives used in formulating themetalworking fluid composition can be blended into the base oil matrixindividually or in various sub-combinations. In one embodiment, all ofthe components are blended concurrently using an additive concentrate(i.e., additives plus a diluent, such as a hydrocarbon solvent). The useof an additive concentrate takes advantage of the mutual compatibilityafforded by the combination of ingredients when in the form of anadditive concentrate.

In another embodiment, the metalworking fluid is prepared by mixing thebase oil matrix with the optional additives and/or additive package(s)at an appropriate temperature, such as approximately 60° C., untilhomogeneous, for use as a straight oil cutting fluid. In yet anotherembodiment, the emulsifying agents may be added to the metalworkingfluid to form an oil-in-water emulsion.

Properties: In one embodiment, the metalworking fluid composition ischaracterized as having reduced mist formation, low foaming tendencyexcellent air release properties, as well as excellent wear properties.The foaming tendency of the metalworking fluids can be measured usingthe ASTM D892-95 foam test. In one embodiment, the metalworking fluidwhen evaluated under ASTM D892-06 method shows a sequence II foamtendency foam height of less than 50 mls. In yet another embodiment, themetalworking fluid shows a sequence II foam height of less than 40 mls.In a third embodiment, a sequence II foam height of less than 30 mls. Ina fifth embodiment, the sequence II foam height is less than 20 mls. Ina six embodiment, none can be measured (0 ml).

In one embodiment, the metalworking fluid shows a sequence I foamtendency by ASTM D 892-03 of less than 100 ml. In another embodiment,the fluid has a sequence I foam tendency of less than 50 ml. In a thirdembodiment, a sequence I foam tendency of less than 30 ml.

In one embodiment, the metalworking fluid has a number of minutes to 3ml emulsion at 54° C. by ASTM D 1401-02 of equal or less than 30. In yetanother embodiment, the fluid has a number of minutes to 3 ml emulsionat 82° C. by ASTM D 1401-02 equal to or less than 60.

Air release properties can be measured using the ASTM D 3427 (2003)method for gas bubble separation time of petroleum oil to measure theability of a fluid to separate entrained gas. In one embodiment, themetalworking fluid has an air release time at 50° C. of less than 0.60minutes as measured according to ASTM D 3427 (2003). In a secondembodiment, an air release time of less than ½ minutes.

In one embodiment, the metalworking fluid exhibits reduced mistformation property and imparts aerosol control or particulate control tothe fluid, e.g., having 5 to 50% mist reduction compared to metalworkingfluids comprising base oil Group I in the prior art. Mist reductionexperiments can be measured according to similar to the aerosol (mist)formation test as described in “Polymer Additives as Mist Suppressantsin Metal Cutting Fluids,” by Marano et al., Journal of the Society ofTribologists and Lubrication Engineers, October 1995, pp. 25-35. In oneembodiment, the metalworking fluid without any addition of anti-mistadditives has an average mist accumulation rate of less than 300 mg/mm³in the first 30 seconds (after start) of the aerosol mist formationtest. In another embodiment, the metalworking fluid without any mistadditive has an average mist accumulation rate of less than 250 mg/mm³in the first 30 seconds of the aerosol mist formation test. In a thirdembodiment, the average mist accumulation rate is less than 200 mg/mm³in the first 30 seconds of the test. In a fourth embodiment, the averagemist accumulation rate is less than 150 mg/mm³ in the first 60 secondsof the test.

In one embodiment, the metalworking fluid composition is readilybiodegradable, with the base oil having an OECD 301D level ranging from30 to 95%.

In one embodiment, the metalworking fluid has a kinematic viscosity at40° C. of 10-14 mm²/s and an OECD 301D biodegrability of >=60%. In asecond embodiment, the composition has a kinematic viscosity at 40° C.of less than 10 mm²/s and an OECD 301D biodegrability of >=80%. In athird embodiment, the composition has a kinematic viscosity at 40° C. ofless than 8 mm²/s and an OECD 301D biodegrability of >=90%. In a fifthembodiment, the metalworking fluid has a biodegradability of at least30% as measured according to OECD 301D.

Metalworking fluids can be characterized as suitable or unsuitable forextreme pressure applications. A fluid that is considered as suitablefor extreme pressure is one that prevents sliding metal surfaces fromseizing under extreme pressure conditions. The seizing of metal surfacesresult from friction between opposing asperities. Asperities aremicroscopic projections on metal surfaces resulting from metalworkingoperations. One technique for measuring extreme pressure properties of afluid is to measure a load force between sliding surfaces which can besustained by lubricant without seizing of the sliding surfaces. Such atechnique is described as a Falex load test, which is an ASTM standardtest for fluid lubricants (ASTM D-3233 (2003)).

In one embodiment, the metalworking fluid is characterized has having aFalex reference wear of less than ten teeth. In another embodiment, themetalworking fluid is characterized as having a Falex reference load ofgreater than about 4,500 pounds force.

In one embodiment, the metalworking fluid is characterized as havingexcellent lubricating property, specifically lubricating surfaces insliding contacts, as measured in a Four-Ball Wear Test per ASTM D4172-94(2004)e1. In one embodiment, the metalworking fluid has a Four-Ball wearscar diameter of less than about 0.07 mm.

In some applications and with the use of isomerized base oils having alow kinematic viscosity, the metalworking fluid is characterized hashaving a smooth liquid flow for excellent circulation in a pump.Moreover, the metalworking fluid has an excellent which can preventfrictional heat from being produced between a tool and a workpiece, sothat the effective tool life can be increased.

Applications: In one embodiment, the metalworking fluid is used in theproduction of semiconductors, plant equipment, and auto parts, etc.wherein the shape of the final object, e.g., silicon wafer or machinepart, is obtained by with or without the progressive removal of metal orsilicon. Non-limiting examples of the operations include cutting,drilling, boring, honing, broaching, grinding, forming, stamping,casting, forging, rolling, piercing, coining, drawing, press forming,deburring, milling, grooving, tapping, chamfering, broaching, reaming,honing, lapping, straightening, and drawing.

In one embodiment of a metalworking operation, the metalworking fluid isapplied to the contact zone between tool and workpiece. The fluid may beapplied by a variety of methods, including immersing the contact zone inthe fluid, spraying the fluid into the contact zone, flooding thecontact zone with fluid, pumping a stream of fluid into the contactzone, periodically wetting the tool or the workpiece with lubricatingfluid, or any means of constantly or intermittently applying thelubricant to the contact zone between the tool and the workpiece.

EXAMPLES

Unless specified otherwise, the compositions are prepared by mixing thecomponents in the amounts indicated in the Examples/Tables. Thecomponents used in the Examples are listed below.

EP agent is a commercially available sulfurized polymerized ester, 10%inactive sulphur extreme-pressure agent.

HYNAP™ N100HTS hydrotreated, naphthenic oil (Group V) is from SanJoaquin Refining Oil, Inc. of Bakersfield, Calif.

Ashland™ 100SN Group 1 oil is from Ashland Inc.

Chevron™ 100R group 2 oil, Chevron™ 100R group 3 oil, and ChevronSynfluid 4 cSt PAO oil are all from Chevron Corporation of San Ramon,Calif.

Additive 2 is a sulfurized vegetable fatty acid ester. Defoamer is anacrylate oligomer antifoam/defoamer. Additive CAS is a commerciallyavailable overbased calcium sulphonate PEP metalworking additivecontaining carbonated alkylbenzene sulfonate. Additive SO is asulfurized olefin.

Mineral seal oil (MSO) having a viscosity of 3.39 mm²/sec at 40° C., andbasestock oils SN 100 (density of 0.864 and viscosity of 20.6 mm²/sec at40° C.), SN 150 and SN 600 (API Group I) are commercially available froma number of sources.

GTL Fischer-Tropsch derived base oils GST0449, FTBO L, FTBO XL, FTBOXXL, and FTBO M are from Chevron Corp. Properties of the Fischer-Tropschderived base oils used in the Examples are shown in Table 3.

Anti-mist agent 1 is a methacrylate copolymer. Anti-mist agent 2 is acommercially available high molecular weight oil soluble polymertackifier.

Examples 1-6

A number of metalworking fluid compositions having components as listedin Table 1 were formulated and their properties were measured usingvarious standard test methods: ASTM D1401-02 for Water Separability ofPetroleum Oils and Synthetic Fluids; ASTM D 3427 (2003) Standard TestMethod for Air Release Properties of Petroleum Oils; and ASTM D892-95Foam Stability Sequence Test. As shown in the table, the exampleincorporating the isomerized base oil shows low foaming tendency (foamheight of nil) and air release property that is comparable if not betterthan the prior art oil (in view of the test repeatability of 1 min.).

TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Group V Group 1 Group 2 Group 3 PAO GTL wt % wt % wt % wt % wt % wt %Sample ID SJR Hynap N100HTS - Group V 95 — — — — — Ashland 100 SN -Group 1 — 95 — — — — Chevron 100 R - Group 2 — — 95 — — — Chevron UCBO4R - Group 3 — — — 95 — — Chevron Synfluid, 4 cSt - PAO — — — — 95 — GTLGST0449 isomerized base oil — — — — — 95 EP agent 5 5 5 5 5 5 KinematicViscosity @ 40° C., cSt 19.91 20.51 20.70 18.30 17.76 18.60 Air Release@50 C., D3427, min 0.72 0.88 0.5 0.42 <0.42 <0.42 Foam Sequence I-III,D892 Seq. I, 24 C., Tendency, ml foam 220 70 80 30 0 0 Seq. I,Stability, ml after 10 min. 0 0 0 0 0 0 Seq. II, 93.5 C., Tendency, mlfoam 30 30 25 20 0 0 Seq. II, Stability, ml after 10 min. 0 0 0 0 0 0Seq. III, 24 C., Tendency, ml foam 140 100 80 40 0 0 Seq. III,Stability, ml after 10 min. 0 0 0 0 0 0 Water Separability, D1401 @ 54C. o-w-e, ml 2/0/78 2/0/78 2/0/78 2/0/78 2/0/78 2/2/76 Time, min 30 3030 30 30 30 Water Separability, D1401 @ 82 C. o-w-e, ml 6/0/74 6/0/745/0/75 9/0/71 7/0/73 6/0/74 Time, min 60 60 60 60 60 60

Examples 7-13

A number of metalworking fluid compositions having components as listedin Table 2 were formulated and their properties were measured/recorded.Examples 11-13 compare the compositions each with 0.25 wt. % of ananti-mist agent added (a high molecular weight oil soluble polymertackifier).

The samples were subject to an aerosol (mist) formation experimentsimilar to the one described in “Polymer Additives as Mist Suppressantsin Metal Cutting Fluids,” by Marano et al., Journal of the Society ofTribologists and Lubrication Engineers, October 1995, pp. 25-35.Basically in the test, metalworking fluid (in 100 mil. sample) wassupplied to a coaxial atomizer's tip through a tube (e.g., ID of 0.0011m) by a syringe pump at constant flow rates up to 0.0084 litre/min.Compressed air was supplied through the annulus between the outer andinner tubes (ID 0.0021 m and OD 0.0013 m, respectively) at flow rates upto 35 litres/min. Mist generated by the atomizer was directed to a longwide plexiglass duct of square cross section or chamber (e.g., a 12″ by12″ by 18″ chamber). The amount of mist generated as a function of time(as mg/mm³ over a duration of 5 minutes) was captured by a dataloggerand recorded. In the experiments, a portable, real time aerosol monitorDataRAM® [MIE Instruments Inc., Bedford Mass.] was used as thedatalogger to continuously quantify the mist levels generated. TheDataRAM is a nephelometric monitor used to measure airborne particleconcentration by sensing the amount of light scattered by the populationof particles passing through a sampling volume.

Most mist was generated for all of the samples at the beginning of thetest. After atomizing, the mist tended to drop to the bottom of thecontainer and thereby showing a drop in the amount of mist collected.

Measurements from the aerosol (mist) formation experiments were plottedin FIGS. 1-3 as a function of time. The results show that generally,metalworking fluid compositions containing Fischer-Tropsch derived baseoils result in significantly less mist formation than the base oils ofthe prior art, with a reduction in mist formation of at least 10% insome examples to up to 75% or more in the first 30 seconds of theaerosol mist formation test. Example 10 with the isomerized base oilperforms better (with reduced mist formation) compared to Example 9 witha mineral group I base oil and even with 2 wt. % anti-mist additive. InFIG. 3, all examples (#11-13) with the addition of a high molecularweight oil soluble polymer tackifier as a powerful (and expensive)anti-mist additive show comparable performance.

TABLE 2 Ex. 11 Ex. 12 Ex. 13 Ex. 7 Ex. 8 Ex. 9 Ex. 10 ZX12A- ZX12B-ZX12C- Components wt. % ZX12A ZX12B ZX46A ZX46B antimist antimistantimist SN 100 51.98 — — — 51.98 — — SN 150 — — 70.98 — — — — SN 600 —— 15 — — — — MSO 36 — — — 36 — — FTBO M — — — 87.98 — — — FTBO L — — — —— — — FTBO XL — 16.21 — — — — 16.21 FTBO XXL — 71.77 — — — 87.98 71.77Anti-mist agent 1 — — 2 — — — — Anti-mist agent 2 — — — — 0.25 0.25 0.25CAS alkylbenzene 4 4 4 4 4 4 4 Sulfurized olefin 2.5 2.5 2.5 2.5 2.5 2.52.5 Additive 2 5.5 5.5 5.5 5.5 5.5 5.5 5.5 Defoamer 0.02 0.02 0.02 0.020.02 0.02 0.02 Visc. @40° C. m²/sec 10.4 9.89 48.12 45.19 10.7 9.61 9.89Density @15° C. .8626 .8264 — — .8626 .826 .826 Visc. @100° C. m²/sec2.84 2.8 — — — — — VI 122 141 — — — — — Flash point ° C. 148 178 — — — —— Color L3.5 L3.5 — — — — —

TABLE 3 FTBO-XXL FTBO-XL FTBO-L FTBO-M BST00449 Properties KinematicViscosity @ 40° C., cSt 7.658 11.16 17.07 34.13 17.74 KinematicViscosity @ 100° C., cSt 2.333 2.988 4.028 6.134 4.12 Viscosity Index124 125 139 156 138 Cold Crank Viscosity @ −40° C., cP 1,525 Cold CrankViscosity @ −35° C., cP 578 1,524 6048 1,596 Cold Crank Viscosity @ −30°C., cP 361 866 3200 941 Pour Point, ° C. −46 −36 −28 −18 −26 n-d-mMolecular Weight, gm/mol (VPO) 314 375 436 508 431 Density, gm/ml 0.80260.8059 0.8122 0.824 0.8128 Refractive Index 1.4485 1.4507 1.454 1.45961.4541 Paraffinic Carbon, % 93.13 96.97 95.82 92.84 95.99 NaphthenicCarbon, % 6.87 3.03 4.18 7.16 4.01 Aromatic Carbon, % 0.00 0.00 0.00 0 0Oxidator BN, hrs 35.9 56.27 39.97 41.02 ANTEK SULFUR <2 <1 <1 <2 LOWLEVEL NITROGEN <0.1 <.1 <0.1 <0.1 Noack, wt. % 60.69 26.8 10.72 3.1510.22 Saybolt Color +33.6 Aromatics Total 0.00261 0 0.00082 COC FlashPoint, ° C. 192 206 226 254 232 SIMDIST TBP (WT %), F. TBP @0.5 583 679726 799 732 TBP @5 622 701 754 831 758 TBP @10 636 709 766 846 770 TBP@20 654 720 780 865 784 TBP @30 667 728 791 880 795 TBP @40 678 735 800894 805 TBP @50 688 741 809 906 813 TBP @60 697 748 818 920 822 TBP @70706 756 828 935 832 TBP @80 715 764 839 952 843 TBP @90 727 774 853 976857 TBP @95 735 782 864 994 867 TBP @99.5 753 802 884 1034 887 FIMSSaturates 72.7 75.3 75 75.3 1-Unsaturation 19.3 23.2 24 23.62-Unsaturation 3.9 1.1 0.8 0.9 3-Unsaturation 2 0.2 0.1 0.14-Unsaturation 1.7 0 0 0 5-Unsaturation 0.5 0 0 0 6-Unsaturation 0 0.20.1 0.1 Branching Index 30.21 28.85 26.95 27.25 Branching Proximity14.05 12.77 14.43 14.83 Alkyl Branches per Molecule 2.17 2.63 2.57 2.9Methyl Branches per Molecule 1.90 2.07 2 2.26 FCI 3.15 3.42 4.5 4.56FCI/END Methyl Ratio 2.50 2.33 3.66 3.1 Alkyl Branches per 100 Carbons9.67 9.83 8.25 9.42 Methyl Branches per 100 Carbons 8.48 7.74 6.41 7.35% Olefins by Proton NMR 0.00 0.12 0.23 0.32 Monocycloparaffin (FIMS1-unsat- 23.88 NMR Olefins) Multicycloparaffin (FIMS 2-Unsat- 0.997396Unsat - HPLC-UV Aromatics) Mono/Multi ratio 23.94

In the absence of EP additives, the GTL base oil alone would providepoor wear protection, as evidenced by the significant wear scar on the 4ball wear test. It could not be used as a metal working fluid withoutdamaging the metal surfaces of both cutting tool and workpiece. Thisdata was obtained by testing of the extra light hydrocarbon liquidderived from highly paraffinic wax which was disclosed in US2006/0201852A1.

TABLE 4 Straight Base Oil Performance Properties (including Gas toLiquid GTL) GTL wt % SJR Hynap N100HTS 0 Ashland 100 SN 0 Chevron 100 R0 Chevron UCBO 4R 0 Chevron Synfluid, 4 cSt 0 LGTL 100 KinematicViscosity @ 40° C., cSt Kinematic Viscosity @ 100° C., cSt 4.12Viscosity Index 138 Four Ball Wear, D4172 Scar diameter, mm 0.75 AirRelease @50 C., D3427, min 0.42 Foam Seq 1, D892 0/0 Tort B Degree ofrusting severe % Rusted >90 No. of spots NA Tort A Degree of rustingsevere % Rusted 100 No. of spots NA

TABLE 5 Compostion % LN GTL 95.00 Syn Ester SE 110 5.00 Total 100.00Kinematic Viscosity @ 40° C., cSt 18.56 Kinematic Viscosity @ 100° C.,cSt 4.246 Viscosity Index 138 Four Ball Wear, D4172 0.633 Scar diameter,mm 0.75

Table 5 shows that the addition of GP additives decreases the wear scaron the four ball wear test.

For the purposes of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages orproportions, and other numerical values used in the specification andclaims, are to be understood as being modified in all instances by theterm “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that may vary depending upon thedesired properties sought to be obtained by the present invention. It isnoted that, as used in this specification and the appended claims, thesingular forms “a,” “an,” and “the,” include plural referents unlessexpressly and unequivocally limited to one referent. As used herein, theterm “include” and its grammatical variants are intended to benon-limiting, such that recitation of items in a list is not to theexclusion of other like items that can be substituted or added to thelisted items.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope is defined bythe claims, and may include other examples that occur to those skilledin the art. Such other examples are intended to be within the scope ofthe claims if they have structural elements that do not differ from theliteral language of the claims, or if they include equivalent structuralelements with insubstantial differences from the literal languages ofthe claims.

All citations referred herein are expressly incorporated herein byreference.

1. A metalworking fluid, which demonstrates resistance to wearcomprising: a lubricant base oil having consecutive numbers of carbonatoms and less than 10 wt % naphthenic carbon by n-d-M, said base oilfurther comprising at least 70% of Fischer-Tropsch derived base oils;and 0.10 to 10 wt. %. of at least an additive selected from the group ofa metalworking fluid additive package; metal deactivators; corrosioninhibitors; antimicrobial; anticorrosion; extreme pressure agents;antifriction; antirust agents; polymeric substances; anti inflammatoryagents; bactericides; antiseptics; antioxidants; chelating agents suchas edetic acid salts, and the like; pH regulators; antiwear agents; andmixtures thereof wherein the metalworking fluid has an average mistaccumulation rate of less than 300 mg/mm3 within 30 seconds after startas measured in an aerosol mist formation test.
 2. The metalworking fluidof claim 1, wherein the metalworking fluid has an average mistaccumulation rate of less than 250 mg/mm3 within 30 seconds as measuredin an aerosol mist formation test.
 3. The metalworking fluid of claim 2,wherein the metalworking fluid has an average mist accumulation rate ofless than 150 mg/mm3 within 30 seconds as measured in an aerosol mistformation test.
 4. The metalworking fluid of claim 1, wherein themetalworking fluid has an average mist accumulation rate of less than150 mg/mm3 within 60 seconds as measured in an aerosol mist formationtest.
 5. The metalworking fluid of claim 1, wherein the metalworkingfluid has a biodegradability of at least 30% as measured according toOECD 301D.
 6. The metalworking fluid of claim 1, wherein the lubricatingbase oil is a Fischer-Tropsch derived base having a kinematic viscosityat 100° C. between 2 mm2/s and 6 mm2/s; a kinematic viscosity at 40° C.between 7 mm2/s and 20 mm2/s; a viscosity index of 120-150; pour pointin the range of −20 and −50° C.; molecular weight of 300-500; density inthe range of 0.800 to 0.820; paraffinic carbon in the range of 93-97%;naphthenic carbon in the range of 3-7%; Oxidator BN of 30 to 60 hours;and Noack volatility in wt. % of 8 to 60 as measured by ASTM D5800-05Procedure B.
 7. The metalworking fluid of claim 1, wherein thelubricating base oil is a Fischer-Tropsch derived base oil: a kinematicviscosity at 100° C. between 5 mm2/s and 7 mm2/s; a kinematic viscosityat 40° C. between 25 mm2/s and 50 mm2/s; a viscosity index of 140-160;pour point in the range of −15 and −25° C.; molecular weight of 450-550;density in the range of 0.820 to 0.830; paraffinic carbon in the rangeof 90-95%.
 8. The metalworking fluid of claim 1, wherein the lubricantbase oil has an average molecular weight between 600 and 1100, and anaverage degree of branching in the molecules between 6.5 and 10 alkylbranches per 100 carbon atoms.
 9. The metalworking fluid of claim 1,wherein the lubricant base oil has a wt. % Noack volatility between 0and
 100. 10. The metalworking fluid of claim 1, wherein the lubricantbase oil has an auto-ignition temperature (AIT) greater than an amountdefined by: 1.6*(Kinematic Viscosity at 40° C., in mm2/s)+300.
 11. Themetalworking fluid of claim 1, wherein the lubricant base oil has anauto-ignition temperature (AIT) greater than 329° C.
 12. Themetalworking fluid of claim 1, wherein the lubricant base oil has aviscosity index greater than 28*Ln(Kinematic Viscosity at 100° C., inmm2/s)+300.
 13. The metalworking fluid of claim 1, wherein the lubricantbase oil has a ratio of weight percent molecules withmonocycloparaffinic functionality to weight percent molecules withmulticycloparaffinic functionality of greater than
 15. 14. Themetalworking fluid of claim 1, wherein the lubricant base oil has atotal weight percent of molecules with cycloparaffinic functionality ofgreater than 10, and a ratio of weight percent molecules withmonocycloparaffinic functionality to weight percent molecules withmulticycloparaffinic functionality of greater than
 15. 15. Themetalworking fluid of claim 1, wherein the lubricant base oil has aKinematic Viscosity at 100° C. of >1.808 mm2/s and a Noack volatilityless than an amount calculated by: 1.286+20 (kv100)−1.5+551.8 e−kv100,where kv100 is the kinematic viscosity at 100° C.
 16. The metalworkingfluid of claim 1, wherein the lubricant base oil comprises greater than3 weight % molecules with cycloparaffinic functionality and less than0.30 weight percent aromatics.
 17. The metalworking fluid of claim 1,wherein the lubricant base oil is greater than 10 wt. % and less than 70wt. % total molecules with cycloparaffinic functionality.
 18. Themetalworking fluid of claim 1, wherein the lubricant base oil has atraction coefficient of less than 0.023 when measured at a kinematicviscosity of 15 mm2/s and at a slide to roll ratio of 40%.
 19. The metalworking fluid of claim 1, wherein the wear scar diameter is less than0.75 mm.
 20. A method for lubricating a workpiece in a metalworkingoperation, the method comprising: supplying to the workpiece acomposition comprising a lubricant base oil having consecutive numbersof carbon atoms and less than 10 wt % naphthenic carbon by n-d-M saidbase oil further comprising at least 70% of Fischer-Tropsch derived baseoils; and 0.10 to 10 wt. %. of at least an additive selected from thegroup of a metalworking fluid additive package; metal deactivators;corrosion inhibitors; antimicrobial; anticorrosion; extreme pressureagents; antifriction; antirust agents; polymeric substances; antiinflammatory agents; bactericides; antiseptics; antioxidants; chelatingagents such as edetic acid salts, and the like; pH regulators; antiwearagents; and mixtures thereof, wherein the lubricating base oil impartsaerosol control or particulate control to the composition for thecomposition to have an average mist accumulation rate of less than 300mg/mm3 within 30 seconds after start as measured in an aerosol mistformation test.
 21. The method of claim 20, wherein the metalworkingfluid has an average mist accumulation rate of less than 250 mg/mm3within 30 seconds after start as measured in an aerosol mist formationtest.
 22. The method of claim 20, wherein metalworking fluid has abiodegradability of at least 30% as measured according to OECD 301D. 23.The method of claim 20, wherein the lubricant base oil is aFischer-Tropsch derived base oil made from a waxy feed, and having akinematic viscosity at 100° C. between 2 mm2/s and 3 mm2/S; a kinematicviscosity at 40° C. between 7 mm2/s and 12 mm2/s; a viscosity index of120-140; pour point in the range of −30 and −50° C.; molecular weight of300-500; density in the range of 0.800 to 0.820; paraffinic carbon inthe range of 93-97%; naphthenic carbon in the range of 3-7%; Oxidator BNof 30 to 60 hours; and Noack volatility in wt. % of 10 to 60 as measuredby ASTM D5800-05 Procedure B.